Structural optimization of a bicycle stem tailored using a monitored bench

Abstract

This study presents the customization of bicycle stems to their cyclists’ specificities by using a factorial plan and generative design approach. Five non-professional cyclists participated in the study. The tests were performed on a home-made static bicycle bench which has instrumented pedals and strain gauges on the handlebars and the saddle. A design of experiment with three parameters on two levels is employed to identify the cyclists with the greatest influence from the bicycle settings. The three parameters are pedaling rate, stem length and saddle height. The responses studied are divided into two categories. The first is focused on the behavior of the structure, via strain gauges and instrumented pedals. The forces applied by the participants on the handlebars, the saddle as well as the pedaling power are investigated. The second category focuses on movements through video recordings. The mean angular amplitude of the knee and hip is studied. It was found that three participants out of five were more sensitive to the modifications of the handlebars’ position and the saddle height. The generative design of the bicycle stem was conducted using the specificities of these three riders as load cases. The optimized stems were validated using finite element analysis. They are very organic, which is way different from the commercially available stems. They are also different from one another, proving that it may be worth looking into this tool to push bike optimization to its maximum, for people sensitives to the geometric settings of their bicycle.